Discovered: July 08, 2002
Updated: October 29, 2008 6:41:54 PM
Also Known As: W32/IRCbot.worm.dll!95744 [McAfee], W32/Spybot.worm!dx [McAfee], Generic BackDoor!csb [McAfee]
Type: Trojan, Worm
Systems Affected: Windows

W32.IRCBot is a detection for worms that spread using Internet Relay Chat (IRC). The IRC connection serves as a back door, allowing an attacker to perform a variety of actions on the compromised computer. An attacker usually gathers a large number of computers infected with W32.IRCBot worms and uses them as a bot network, controlled through IRC.

The use of IRC separates threats from their traditional back door and worm counterparts in that the hacker does not issue commands directly to the back door. Rather they are routed through the IRC server and channel, and then on to the compromised computer. Without the IRC server or channel, the attacker is unable to control the compromised computer.


Antivirus Protection Dates

  • Initial Rapid Release version July 09, 2002
  • Latest Rapid Release version July 15, 2018 revision 005
  • Initial Daily Certified version July 09, 2002 revision 007
  • Latest Daily Certified version July 15, 2018 revision 002
  • Initial Weekly Certified release date July 10, 2002

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Gor Nazaryan

Discovered: July 08, 2002
Updated: October 29, 2008 6:41:54 PM
Also Known As: W32/IRCbot.worm.dll!95744 [McAfee], W32/Spybot.worm!dx [McAfee], Generic BackDoor!csb [McAfee]
Type: Trojan, Worm
Systems Affected: Windows

W32.IRCBot is a detection for worms that spread using Internet Relay Chat (IRC). The IRC connection serves as a back door, allowing an attacker to perform a variety of actions on the compromised computer. An attacker usually gathers a large number of computers infected with W32.IRCBot worms and uses them as a bot network, controlled through IRC.


Background information
Threats that utilize IRC have been around for a long time and have gone through some changes over the years. In the past, such threats would require a computer with an IRC client previously installed in order to function. Later iterations bundled a hacked copy of mIRC, a popular and readily available IRC client. Today, most W32.IRCBot worms contain their own IRC client embedded within the worm.


What is IRC?
In a nutshell, Internet Relay Chat (IRC) is a computer network commonly used for communication, sharing files, and sending out distributed commands to computer networks. An IRC network is comprised of servers that contain “channels”, which are organized by topic. Threats like W32.IRCBot worms use IRC to spread and to carry out back door functions.

For a more detailed description of IRC, see the Internet Relay Chat page on Wikipedia.


What does the worm do?
The primary purpose of W32.IRCBot worms is to open a back door, allowing an attacker to issue commands to the compromised computer. While the functions that can be carried out are largely arbitrary (a back door generally provides full control of the computer), the following list highlights some functions that are often carried out by the back door in W32.IRCBot worms:

  • Perform distributed denial of service (DDoS) attacks
  • Set up a proxy server to route traffic through the computer
  • Spread the worm to other computers
  • Collect information (system and personal) from the computer and any storage device attached to it
  • Terminate or run tasks and processes
  • Download and execute additional files
  • Upload files and other content
  • Report on status
  • Open remote command line shells
  • Change computer settings
  • Shut down or restart the computer


Why would a worm use IRC?
Relaying the commands through an IRC server provides the attacker with a level of anonymity not as easily obtained by connecting directly to the threat’s back door. IRC also allows an attacker to control a large number of computers as a botnet. Since each threat compromised by a particular W32.IRCBot worm logs into a predetermined IRC channel, an attacker can then send a command to the channel, and on to all the computers in the botnet.


How does the worm spread?
The worms often use the classical methods of propagation, including the following:
  • Copying itself to removable drive and network shares. In this case the worm also creates autorun.inf files so that the worm is executed when the drive is accessed on another computer.
  • Exploiting known vulnerabilities. The worm may look for other computers on the network and then attempt to gain access using software exploits.
  • Creating copies of itself in file-sharing folders. These often have file names meant to entice other users of the file-sharing network to download and execute the worm on their computer.


Are there any tell-tale signs?
The default port for IRC communication is 6667, and server communication may utilize ports in the 6660-6669 range. However, W32.IRCBot worms often use unusual port numbers to communicate with their IRC servers. Any unexpected IRC communication that falls outside of the standard realm should be regarded as suspicious. Firewalls or network monitoring tools may show network traffic to or from unusual remote addresses.


What are the risks?
The back door component of these worms poses a relatively high risk of damage or loss to the user if they can remain undetected and active for a significant time. On the lower end of the scale is annoyance through the loss of bandwidth or performance due to actions such as spreading to other computers or proxying traffic. On the upper end of the scale the risks include identity theft and the loss of money from online accounts due to the theft of login credentials.


What can I do to minimize the risks?
As a general rule, users should always run up-to-date antivirus software with real-time protection such as Norton Antivirus, Norton Internet Security, Norton 360 or Symantec Endpoint Protection . In addition, a firewall -- or better still, an Intrusion Prevention System (IPS) -- will help to block back channel activities initiated by these types of malicious programs. Program controls such as those found in Symantec Endpoint Protection can also help to prevent unknown programs such as these from executing in the first place.

Users should disable the AutoRun feature or be sure to upgrade to a recent version of Windows that has AutoRun disabled by default for non-optical removable media.

Ensure that your computer is up-to-date with the latest patches for both your operating system and the software installed. Doing so reduces the chances of a threat exploiting a known vulnerability.


How can I find out more?
Advanced users can submit a sample to Threat Expert to obtain a detailed report of the system and file system changes caused by a threat.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Gor Nazaryan

Discovered: July 08, 2002
Updated: October 29, 2008 6:41:54 PM
Also Known As: W32/IRCbot.worm.dll!95744 [McAfee], W32/Spybot.worm!dx [McAfee], Generic BackDoor!csb [McAfee]
Type: Trojan, Worm
Systems Affected: Windows

You may have arrived at this page either because you have been alerted by your Symantec product about this risk, or you are concerned that your computer has been affected by this risk.

Before proceeding further we recommend that you run a full system scan . If that does not resolve the problem you can try one of the options available below.



FOR NORTON USERS
If you are a Norton product user, we recommend you try the following resources to remove this risk.

Removal Tool


If you have an infected Windows system file, you may need to replace them using from the Windows installation CD .


How to reduce the risk of infection
The following resources provide further information and best practices to help reduce the risk of infection.


FOR BUSINESS USERS
If you are a Symantec business product user, we recommend you try the following resources to remove this risk.

Identifying and submitting suspect files
Submitting suspicious files to Symantec allows us to ensure that our protection capabilities keep up with the ever-changing threat landscape. Submitted files are analyzed by Symantec Security Response and, where necessary, updated definitions are immediately distributed through LiveUpdate™ to all Symantec end points. This ensures that other computers nearby are protected from attack. The following resources may help in identifying suspicious files for submission to Symantec.


Removal Tool

If you have an infected Windows system file, you may need to replace them using from the Windows installation CD .


How to reduce the risk of infection
The following resource provides further information and best practices to help reduce the risk of infection.
Protecting your business network



MANUAL REMOVAL
The following instructions pertain to all current Symantec antivirus products.

1. Performing a full system scan
How to run a full system scan using your Symantec product


2. Restoring settings in the registry
Many risks make modifications to the registry, which could impact the functionality or performance of the compromised computer. While many of these modifications can be restored through various Windows components, it may be necessary to edit the registry. See in the Technical Details of this writeup for information about which registry keys were created or modified. Delete registry subkeys and entries created by the risk and return all modified registry entries to their previous values.

Writeup By: Gor Nazaryan